<style>
  body {
    margin: 0;
    padding: 0;
  }

  .container {
    width: 100%;
    height: 200px;
    position: relative;
  }

  .left {
    width: 300px;
    height: 200px;
    background-color: green;
    position: absolute;
    left: 0;
  }

  .right {
    width: 300px;
    height: inherit;
    background-color: red;
    position: absolute;
    right: 0;
  }

  .center {
    background-color: rosybrown;
    height: inherit;
    position: absolute;
    left: 300px;
    right: 300px;
    margin-left: 10px;
    margin-right: 10px;
  }
</style>
</head>

<body>
  <div class="container ">
    <div class="left"></div>
    <div class="center"></div>
    <div class="right"></div>

  </div>